The present invention relates generally to alarm devices and is more specifically directed to devices that can be temporarily placed on conventional door knobs to act as burglar alarms, but which can be converted to an alarm for a window or sliding glass door, or the like.
Alarm devices for attachment to door knobs for sounding alarms when anyone attempts to enter a door have been suggested in a variety of forms. Typically, these alarms slide over and engage a door knob in a sufficiently secure manner and has to be rotated when the door knob is rotated, thereby actuating a switch such as a mercury switch, located in the burglar alarm housing. Other such alarms may be held to the door knob with a latching or spring-loaded device, or may be bolted to the door knob for actuating a separate alarm. Typical prior art door knob alarms may be seen in U.S. Pat. No. 3,488,651, to Brenner, for a portable alarm which has a bracket which clips over a door knob, and includes a mercury switch, which is actuated by the rotation of the alarm housing. The U.S. Pat. No. 3,725,892, to Faltico, teaches a door knob burglar alarm using mercury switches which has a receptacle in the housing for slipping over the door knob, while the Birrenkott U.S. Pat. No. 3,327,300, provides a door knob burglar alarm for suspension from a door knob which is actuated by an off-center, over balance, when the door knob is turned in either direction. A patent to Fontaine, U.S. Pat. No. 3,623,063, has an alarm which is attached to a door and has a handle which extends up over the door knob and is actuated by a change in the frequency of an oscillator by the rotation of the door knob, while the Seely U.S. Pat. No. 2,791,763, suspends a burglar alarm to a door knob with a switch which incorporates the knob so that rotating the knob shifts the housing and a support for the housing to complete a circuit through the door knob. The Kreuger U.S. Pat. No. 2,640,894, teaches a burglar alarm suspended from a door knob which includes an extension for a close-by window. Other door knob burglar alarms include the Miller U.S. Pat. No. 2,423,610, which includes an extension connection for attaching a suction cup to a nearby window pane or door, and the Fruehauf U.S. Pat. No. 704,247, having an extension attached to the door knob for actuating an alarm circuit, and the Getto U.S. Pat. No. 775,723, for an electric burglar alarm, and the Hausser U.S. Pat. No. 1,534,589, for an electric door knob alarm.
In contrast with these prior door knob burglar alarms, the present invention provides for a door knob alarm which is easily connected to a door and which may be quickly removed and carried along when staying in motels, hotels, and other accomodations when away from home, and which may be quickly converted for use as a window or sliding glass door alarm; and which has a simplified alarm sensor which may be quickly reset or disabled through a single cam-actuated switch.